"budget is not huge" is the sticking point.
If you get lucky, maybe
you'll find someone giving away a suitable system. If you have to buy
it piece by piece, (CPU, memory, disk controller, disk drive), it
most likely will cost far more than $1000.
It's doable, I think. An 11/34A CPU box with cards, power supply, some
cables, programmer's front panel, untested, just went on eBay for $203
a few minutes ago.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7501604120
Assuming it turns out to be reasonably working, you'd need additional
cables (I'm guessing, but seems a good bet), and disk drives.
De